Vulnerability-Lookup

CVE-2025-62727 (GCVE-0-2025-62727)

Vulnerability from cvelistv5 – Published: 2025-10-28 20:14 – Updated: 2025-11-04 17:41

Title

Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse

Summary

Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-407 - Inefficient Algorithmic Complexity

Assigner

GitHub_M

References

4 references

URL	Tags
https://github.com/Kludex/starlette/security/advi…	x_refsource_CONFIRM
https://github.com/Kludex/starlette/commit/4ea6e2…	x_refsource_MISC
https://github.com/Kludex/starlette/commit/69ed26…	x_refsource_MISC
https://github.com/Kludex/starlette/releases/tag/0.49.1	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
Kludex	starlette	Affected: >= 0.39.0, < 0.49.1

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2025-62727",
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      "status": "final",
      "title": "starlette: Starlette DoS via Range header merging",
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      "version": "3"
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    "suse_vex": {
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      "product_status:known_not_affected": "2",
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      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-62727.json",
      "version": "11"
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}

ubuntu-cve-2025-62727

Vulnerability from osv_ubuntu

Published

2025-10-28 21:15

Modified

2026-05-20 15:22

Summary

Details

Severity

7.5 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2025-62727	REPORT
	https://www.cve.org/CVERecord?id=CVE-2025-62727	REPORT
	https://github.com/Kludex/starlette/security/advi…	REPORT
	https://github.com/Kludex/starlette/commit/4ea6e2…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-starlette",
            "binary_version": "0.18.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "starlette",
        "purl": "pkg:deb/ubuntu/starlette@0.18.0-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.14.1-1",
        "0.16.0-1",
        "0.18.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-starlette",
            "binary_version": "0.31.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "starlette",
        "purl": "pkg:deb/ubuntu/starlette@0.31.1-1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.30.0-1",
        "0.31.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-starlette",
            "binary_version": "0.46.1-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "starlette",
        "purl": "pkg:deb/ubuntu/starlette@0.46.1-3?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.46.1-2",
        "0.46.1-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-starlette",
            "binary_version": "0.50.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "starlette",
        "purl": "pkg:deb/ubuntu/starlette@0.50.0-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.46.1-3",
        "0.50.0-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette\u0027s FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial\u2011of\u2011service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.",
  "id": "UBUNTU-CVE-2025-62727",
  "modified": "2026-05-20T15:22:58Z",
  "published": "2025-10-28T21:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-62727"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-62727"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-62727"
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2025-62727 (GCVE-0-2025-62727)

ubuntu-cve-2025-62727

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature